Wireless communications network base station extension

ABSTRACT

Apparatus and methods to permit the deployment of wireless base stations, where a deployed remote base station is backhauled to the core network over a wireless connection to an operatively attached donor base station using protocols that encapsulate backhaul communications within standard subscriber communication protocols.

RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication No. 60/960,902, filed on Oct. 19, 2007, by Altshuller et al.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to managed wireless communicationnetworks, and more particularly, but not exclusively to WiMAX networks.

A number of standards have been developed in recent years for providingwireless network access. These include such standards as the IEEE 802.16family (i.e., WirelessMAN, also known as WiMAX), HIPERMAN, WiBro, CDMAfamily (including 3GPP2 for CDMA2000), GSM family (including 3GPP forGSM) and 3GPP systems generally. These networks provide connectivitythrough the deployment of Base Stations (CBS). Each BS contains theequipment necessary to provide wireless radio communication according tothe BS's supported standards. Typically, this includes an antenna andtwo-way radio transmission equipment.

The BS provides radio coverage of a geographic area to providecommunication services to client devices. A client device is known as aSubscriber Station (SS). The SS may be either fixed or mobile andcommunicates via radio frequencies with the BS. A mobile SS is oftencalled a mobile subscriber (MS) for short.

As an essential part of its operation, the BS provides backhauling tothe network. In the context of this disclosure, “backhauling” refers to:(1) the physical connection between a base station and a core network(such as the Internet), and (2) the bi-directional transmission oftraffic (signaling and data) from the core network to the base stationand vice versa over the physical connection. Furthermore, “backhaulcommunications” refers to the network interface, and communicationsthereon, between a base station and a core network (e.g., in WiMAX,interface and communications defined by R6 and R8). “Backhaul” and“backhauling” are sometimes abbreviated as “BH.”

The traffic from and to the base station relative to the core networkmay include both traffic for or from a base station and traffic for orfrom subscriber stations subscribed (i.e., connected) to the basestation.

It should be noted that the term “core network,” as used in thisdisclosure, refers to any network to which a base station is connectedvia a backhaul link. When necessary, other components of the rest of thenetwork, such as a gateway, may be shown explicitly.

Backhauling is accomplished over traditional communicationsinfrastructure. The current art uses both wired (e.g., leased lines,copper, or fiber-optic cables) and wireless (e.g., microwave orsatellite) connections.

According to the current art, installing a new base station requires theconcomitant installation of backhauling infrastructure with itsattendant costs and administrative issues. These costs andadministrative issues can be considerable. For example, it may requirelaying cables, which often require governmental approvals and obtaininglegal right-of-way through public or private property. In remotelocations, the logistics for deploying a backhaul link may beprohibitively costly or difficult.

In the WiMAX field, for example, short-range base stations have beenintroduced. A similar approach can be used with any managed wirelessnetwork. A short-range BS is sometimes called a micro-base station or apico-base station. These short-range, relatively inexpensive BSs havethe potential to accelerate the penetration of WiMAX technology andexpand the areas where it is available. However, a micro- or pico-basestation must still be backhauled to a core network to provideconnectivity to the Internet or other core network. Despite therelatively low cost of the short-range BS, the total deployment costmust take the cost of the backhaul link into account as well. As notedabove, the cost of the backhaul link can be considerable—enough topreclude the deployment of a short-range base station in some cases.

The same applies to conventional, long-range base stations, as well,i.e., the costs associated with the requisite backhaul link may besufficient to undermine the economic justification for deployment.

An alternative way to increase the coverage for a wirelesscommunications network is to install a wireless repeater, rather than anew base station. A repeater is a device that boosts and amplifies theincoming radio signals and retransmits them over an extended area. Inthis sense, the repeater acts as an extension of the existing basestation. As such, it does not require its own backhauling link. On theother hand, a repeater does not provide independent control. It simplyreplicates the policies of an existing base station.

SUMMARY OF THE INVENTION

The present inventors have observed that according to the current art,there are only two ways to extend the coverage of a wireless network:(1) deploy a new base station and pay the costs and administrativeoverhead of the requisite backhaul link, or (2) use a repeater andforego the ability to control and manage the extended area. Embodimentsof the present invention provide apparatus and methods to overcome theselimitations of the current art.

This disclosure describes apparatus and methods to permit the deploymentof wireless base stations anywhere within broadcasting range of anappropriately configured existing base station. The backhauling of thenewly deployed base station is accomplished in-band on the air interfacenormally used for subscriber communications with the existing basestation using protocols that encapsulate backhaul communications withinstandard subscriber communication protocols. This type of backhauling iscalled “in-band Backhauling”.

According to one aspect of the present invention there is provided adevice for use in a wireless managed communication network, said devicecomprising (a) a first interface unit for interfacing with a first basestation, said first interface unit providing a standard backhaulinginterface for backhauling from the first base station, and (b) a secondinterface unit for interfacing with a second base station, the secondbase station being configured to provide backhauling from and to thefirst base station and from and to a core network, such that the firstand second interface units and the second base station jointly provide achannel for backhauling from the first base station.

According to another aspect of the present invention there is provided afirst base station for use in a wireless managed communication network,said first base station comprising (a) a backhauling unit for providinga backhauling communication channel, and (b) an interface unit,associated with said backhauling unit and configured to communicate witha second base station, thereby to make said backhauling communicationchannel available to said second base station.

According to another aspect of the present invention there is providedan augmented base station for use in a managed wireless communicationsnetwork, said augmented base station comprising (a) anin-band-backhauling device, and (b) a first base station forcommunicating with subscriber stations, wherein said in-band-backhaulingdevice comprises (a) a first interface unit for interfacing with saidfirst base station, said first interface unit providing a standardbackhauling interface for backhauling from the first base station, and(b) a second interface unit for interfacing with a second base station,the second base station being configured to provide backhauling from andto the first base station, and from and to a core network, such that thefirst and second interface units and the second base station jointlyprovide a channel for backhauling from the first base station, and saidfirst base station is further configured to communicate with a thirdbase station, thereby to make said channel for backhauling available tosaid third base station.

According to another aspect of the present invention there is provided amethod for controlling flow of traffic in a communication network, wheresaid traffic includes messages of a first type encapsulated withinmessages of a second type, and said first type messages include at leastone parameter defining control of said flow, said method comprising:examining a second type message to discern the contents of anencapsulated first type message, recognizing said parameter within thefirst type message, adjusting the flow of traffic in accordance with theparameter.

According to another aspect of the present invention there is provided aproxying device for proxying network elements in a communicationnetwork, said network operating with at least two protocol layers, saidlayers comprising a lower layer and a higher layer, said networkcomprising (a) a communication link between a first and a second linkingunit, said linking units communicating at the higher protocol layer, (b)a first remote device connected to the first linking unit andcommunicating with said first linking unit according to the lowerprotocol layer, and (c) a second remote device connected to the secondlinking unit and communicating with said second linking unit accordingto the lower protocol layer, said first linking unit incorporating oneof said proxying device, said proxying device configured to representand act on behalf of said second remote device with respect tocommunications with the first remote device.

Unless otherwise defined, all technical and scientific terms andabbreviations used herein have the same meaning as commonly understoodby one of ordinary skill in the art to which this invention belongs. Thematerials, methods, and examples provided herein are illustrative onlyand not intended to be limiting.

Implementation of the method and system of the present inventioninvolves performing or completing certain selected tasks or stepsmanually, automatically, or a combination thereof. Moreover, accordingto actual instrumentation and equipment of preferred embodiments of themethod and system of the present invention, several selected steps couldbe implemented by hardware or by software on any operating system of anyfirmware or a combination thereof. For example, as hardware, selectedsteps of the invention could be implemented as a chip or a circuit. Assoftware, selected steps of the invention could be implemented as aplurality of software instructions being executed by a computer usingany suitable operating system. In any case, selected steps of the methodand system of the invention could be described as being performed by adata processor, such as a computing platform for executing a pluralityof instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin order to provide what is believed to be the most useful and readilyunderstood description of the principles and conceptual aspects of theinvention. In this regard, no attempt is made to show structural detailsof the invention in more detail than is necessary for a fundamentalunderstanding of the invention, the description taken with the drawingsmaking apparent to those skilled in the art how the several forms of theinvention may be embodied in practice.

In the drawings:

FIG. 1 is simplified block drawing showing the basic components of aRecipient Function Unit (RFU) for in-band Backhauling according to anembodiment of the present invention.

FIG. 2 is a simplified block drawing showing the basic components of adonor base station according to an embodiment of the present invention.

FIG. 3 is a simplified block diagram showing an overview of a wirelessnetwork comprising a donor base station and a remote base station,according to an embodiment of the present invention.

FIG. 4 shows an end-to-end protocol stack for R6/R8 control and R6 (GRE)user traffic according to a WiMAX embodiment of the present invention.

FIG. 5 illustrates additions made to a standard inter-BS handover (alsoknown as “handoff”) process from a Remote Base Station to a Donor BaseStation according to an embodiment of the present invention.

FIG. 6 illustrates additions made to a standard inter-BS handoverprocess, from a Donor Base Station to a Remote Base Station according toan embodiment of the present invention.

FIG. 7 shows a network entry procedure for a Recipient Function Unitaccording to an embodiment of the present invention.

FIG. 8 shows an initial network entry procedure of a mobile subscriberto a Remote Base Station, including special handling between an RFU anda Donor Base Station (DBS) according to an embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present embodiments comprise apparatus and methods for

-   -   1. a Donor Function Unit (DFU), which is incorporated into an        ordinary base station so that the base station becomes a Donor        Base Station (DRS),    -   2. a Recipient Function Unit, a stand-alone module that        communicates with one or more Remote Base Stations (RBS) on the        one hand, and over an air interface with the DBS on the other        hand, and    -   3. Various methods and protocols for communication between        components of a network incorporating a DBS and RFU.

In short, a standard base station, backhauled to the communicationsnetwork in a conventional fashion, is augmented with a Donor FunctionUnit (DFU) making it a Donor Base Station (DBS). The DFU communicateswith one or more Remote Base Stations (RBS) through the agency of astand-alone Recipient Function Unit (RFU).

The DFU and RFU are the two ends of a virtual backhaul link (alsoreferred to as virtual channel, virtual segment, and virtual pipe) fromthe DBS to the RFU. This virtual backhaul link is also referred to as an“in-band backhaul link” or “in-band backhaul segment” and the use of itis also referred to as “in-band backhauling”. Additionally, a RemoteBase Station connected through an in-band backhaul link is said to be“in-band-backhauled” or “selif-backhauled.”

It should be noted that an RBS is a completely ordinary base station inevery respect. It is distinguished as an RBS only by virtue of beingconnected to the network through the RFU. If it were not connectedthrough an RFU, it would not be called an RBS.

The fact that the RBS is connected through an RFU is completelytransparent to the RBS and its operation and functionality areunchanged. It is called a Remote BS in terms of its relative location inthe network topology in the sense that it is more remote from the corenetwork than the DBS serving the RBS. A Remote Base Station is alsoreferred to as a “Peripheral Base Station.”

The virtual backhaul link functions like an ordinary backhaul link and,from the perspective of both an RBS and the access components of thecore network (e.g., an ASN Gateway, also called “ASN GW”), the virtualbackhaul link is transparent. It is “virtual” in the sense that the DFUand RFU create it in-band vis-à-vis ordinary subscriber wirelesscommunications (e.g., in-band R1 for WiMAX).

The structure and operation of the RFU and DFU are explained in greaterdetail below.

Note that an RBS may also have a traditional, fixed backhaul link, inwhich case it is in-band-backhauled only with respect to a link providedthrough the RFU and DBS.

It should also be noted that in some embodiments, the RBS and RFU may beconstructed as a single, standalone device.

The principles and operation of an apparatus and method according to thepresent invention may be better understood with reference to thedrawings and accompanying description.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

For convenience and ease of explanation, many of the embodimentsdiscussed in this disclosure are described in terms of their applicationin a WiMAX network and using IP (Internet Protocol) or the Open SystemsInterconnection Basic Reference Model (“OSI Reference Model” or “OSIModel”). The use of WiMAX, IP, and OSI Model terminology should not beconstrued as limiting the invention to embodiments within those domains.Rather the invention's applicability to any managed wireless networkwill be evident to one trained in the art and the use of the exampleterminology is only to aid the reader in understanding various aspectsof the invention.

For example, the term “R6” is used to describe the interface andprotocols for communication between a base station and an ASN gateway;however the invention applies equally to any embodiment of an interfaceand protocol for communicating between a base station and a core networkthrough a network access component such as a gateway. Similarly, otherWiMAX-related terms are used, but should be understood as examples onlyand not limiting to WiMAX embodiments.

Reference is now made to FIG. 1, which illustrates a simplified view ofan RFU 150. An RFU is a device that performs two functions:

-   -   1) The RFU communicates with a DBS to jointly create a virtual        backhaul link between the DBS and the RFU, and    -   2) The RFU communicates with one or more RBSs to provide a        backhaul link connection between the RBS and the DBS using the        virtual backhaul link.

In the presently described embodiment, the RFU 150 is connected to anRBS 160. The RBS 160 is a standard base station.

The RFU 150 comprises two interfaces. On the one hand, it provides tothe RBS 160 a standard backhauling (BH) interface 152. The BH interface152 (shown shaded) is connected to the RBS 160 in a standard way,including hard-wired or connected through any Layer 2 (L2) or Layer 3(L3) (i.e., data link layer or network layer, respectively, per the OSIReference Model) transport mechanism (e.g. by connecting the RBS to anL2/L3 cloud to which the RFU is also connected and establishing aconnection between the RBS and the RFU). The BH interface 152 in the RFU150 handles bidirectional backhaul communications and protocols for theRBS 160. On the other hand, the RFU 150 also includes a DBSair-interface 154 (shown with hatching) to communicate with a DBS 110.An attribute of the communication between the RFU's DBS air-interface154 and the DBS 110 in the presently described embodiment is that thecommunications and protocols are consistent with those of an ordinarysubscriber station using SS communications (e.g., R1 for WiMAX).

As part of its operation, the RFU encapsulates all backhaulcommunication data from an RBS within SS communication data beforetransmission to the DBS (and its inverse, i.e., de-encapsulation forreceived communication destined for an RBS). In the case of anembodiment for WiMAX, for example, all network reference points andinterfaces (R6 and R8) would be encapsulated within R1.

Depending upon the embodiment, encapsulation may take place in the BHinterface 152 or the DBS air interface 154 or in another component (notshown) of the RFU.

The encapsulation of communications between the RFU and the DBS providesthe virtual backhaul link.

There may also be communications directly between the DBS and the RFU,for example when managing a hand-over of a mobile subscriber station(MS) between a DBS and an RBS.

Reference is now made to FIG. 2, which illustrates certain features ofthe DBS 110. The DBS 110 is configured with a backhaul link 112 to acore network 130. As described above, the backhaul link 112 provides aconnection ftom the DBS 110 to the network 130 and the backhaul link 112carries traffic from the DBS 110 to the network 130 and from the network130 to the DBS 110.

The DBS 110 also incorporates logic, in the form of a Donor FunctionUnit (DFU) 114 to handle communication from and to an RFU 150. Inparticular, one of the features of the DFU 114 is that it performs afunction similar to that of the RFU 150. The DFU 114 receivesencapsulated BH communications from the RFU 150 and de-encapsulates themfor further transmission from the DBS 110 to the network 130.Correspondingly, the DFU 114 receives from the network backhaulcommunications that are destined for an RBS. The DFU 114 encapsulatesthe RBS-destined BH communications before transmission to the RFU 150.

Thus, the RFU and the DFU (within the DBS) create an in-band backhaullink and provide to the RBS a transparent backhauling channel to thenetwork, obviating the need for additional backhaul infrastructure toconnect the RBS to the network.

Reference is now made to FIG. 3, which illustrates a simplified view ofa wireless network, including a Donor Base Station 110, Remote BaseStations (RBS) 160, a Recipient Function Unit (RFU) 150, mobilesubscriber stations (MS) 140 a and 140 b, and a gateway 120 to a corenetwork 130. In the presently described embodiment, the DBS 110, isbackhauled via a link 115 to the gateway 120 and the gateway 120 is, inturn, connected via a link 125 to the network 130 (for example, thiscould be the Internet or a cellular communications network or any othernetwork).

The DBS 110 communicates, in the usual fashion known in the art, withthe network 130 to which it is backhauled. Similarly, the DBS 110communicates with Subscriber Stations (SS) in the conventional fashion,such as the shown Mobile Subscriber stations (MS) 140 a.

In addition, the DBS incorporates a Donor Function Unit (not shown, seedescription above) that enables it to provide in-band backhaulingservice to one or more Remote Base Stations 160. Such provision ofbackhauling service is described above.

In the illustrated embodiment, the RBS 160 is an ordinary base station(BS) connected to the Recipient Function Unit (RFU) 150. The RBS 160communicates in the ordinary fashion known in the art for a backhaulingconnection with the RFU 150. Furthermore, it communicates in the usualfashion known in the art with SSs, such as the MSs 140 b.

With respect to the RBS 160, the RFU 150 and the DBS 110 are bothtransparent, i.e., the RBS 160 communicates with the gateway 120 asthough the RBS 160 were backhauled directly to the gateway in theconventional fashion. Similarly, with respect to the gateway 120, also,the DBS 110 and the RFU 150 are transparent.

With respect to the DBS 110, one aspect of the RFU 150 is that itoperates as a special-purpose SS. Communication between the RFU 150 andthe DBS 110 is carried out in the conventional fashion according to theappropriate embodiment (e.g., R1 for WiMAX).

For both the RBS 160 and the gateway 120, the existence of a virtualchannel 180 is completely transparent. Each operates in blissfulignorance of the virtual channel's existence.

In other words, a feature of the RFU 150 and the DBS 110 is that theyprovide the virtual channel 180 for backhaul communications 190 throughthe RFU 150 and the DBS 110. As described above, the RFU 150encapsulates outgoing backhaul communications within standard SScommunication and de-encapsulates incoming backhaul communications. TheDBS 110, for its part, provides the reciprocal functionality,encapsulating backhaul communications before transmitting to the RFU 150and de-encapsulating communications received from the RFU 150 beforetransmitting them to the gateway 120. The immediately forementionedprocess creates the virtual channel 180 for providing a backhaulcommunications 190 between the RBS 160 and the gateway 120, as shownschematically in FIG. 3. This virtual channel 180 may also be thought ofas a virtual pipe, through which BH communications 190 flow in bothdirections. The overall effect is to create a virtual backhaul link forRBSs connected to the RFU 150.

Although the description above of FIG. 3 refers to several RBSs servedby the RFU, in other embodiments a single RBS may be served by one RFU.

Also, although the description of the above-described embodiment is fora DBS connected directly to the backhauling infrastructure, in otherembodiments, the DBS may itself be connected through an RFU, i.e. a DBSmay be part of an RBS with respect to another DBS, creating one or morechains (of arbitrary length). For example, a simple chain would beDBS-RBS/DBS-RBS. Similarly, other configurations are possible and withinthe scope of the present disclosure, as will be understood by onetrained in the art.

To gain a greater understanding of the presently described embodiments,following are some details of embodiments used for a WiMAXimplementation. As noted, it should be understood that the basicprinciples, as described here, can be applied to any managed wirelessnetwork (such as, but not limited to, cellular telephone networks,HIPERMAN, and WiBro) to achieve similar results.

With respect to WiMAX-related embodiments, the following features arenow described. As noted above, WiMAX and other embodiments are used asexamples and are not intended to limit the scope of the disclosure.

1. R6 control delivery between an RBS and an ASN gateway.

2. R6 data path (or session) delivery between an RBS and an ASN gateway.

3. A data path (session) management extension between an RBS and a DBS.

4. Certain network addressing issues.

These aspects are described in the following sections.

In FIG. 4 is shown the protocol stack for end-to-end R6/R8 control andR6 data path delivery respectively for a preferred embodiment. As shownin the figure, the RFU and the DBS's DFU operate on the indicatedcommunications in the protocol stack (as indicated by the linesoverlaying the respective layers in the stack of each unit). Thecommunication between the RFU and the DBS accomplish “R6 over R1”communication, i.e., the R6, or network interface communication (e.g.,between BS and ASN gateway) is transported between the RFU and the DBSusing (i.e., encapsulated within) R1, which is an SS air interfaceprotocol.

In the presently described embodiment, the R6 and R8 control messages,as well as R6 tunneling (e.g., GRE) of the user's traffic isencapsulated within an R1 data connection. The encapsulation includes aBH header and the R6 control message. The BH header comprises, at aminimum, source and destination identifiers (e.g., BS and gateway).

According to a feature of the presently described embodiment, there ismapping of a bearer data stream on a dedicated R1 data connectionaccording to quality of service (QoS) attributes. When considering QoSattributes, the BH header may also include Session ID (e.g., GRE Key)and may replicate sequence numbering from the GRE header (for dataintegrity support).

According to another feature of the presently described embodiment,there is provided session management negotiation between the RFU and theDBS. This negotiation includes establishment and release of an SS (e.g.,an MS). and its sessions. For example, this negotiation may be based onan extension of the 802.16e MAC standard. Examples of the negotiationfor establishment and release of a session are shown in FIG. 5, FIG. 6,and FIG. 8. In the figure is shown an example for the RFU initiating theestablishment and release of a session. It should be noted, however,that the DBS may also initiate establishment and release of a session.It should also be noted, that either the DBS or RFU may apply policiesduring the negotiation. The policies may include, but are not limitedto, various QoS parameters for a specific service flow. The QoSparameters may include, for example, change of rate and delay.

Though not required, for purposes of efficiency from a radioperspective, it is also possible to use a single CID (connection ID) formultiple users and sessions.

Both the RFU and the DBS may incorporate IP address resolution in orderto reconstruct the IP header of the control and data packets. Theaddress resolution is based on various bindings resulting from the BHlayer as described above.

Another feature of the presently described embodiment is that itsupports header compression according to the methods known in the art(e.g., standard WiMAX header compression).

As noted earlier, an advantage of the present embodiment is the abilityto manage SS load between a DBS and one or more operatively connectedRBSs. FIG. 5 shows an example of an MS handover (HO) procedure from anRBS (acting as the Serving BS) to a DBS (acting as Target BS) accordingto a preferred embodiment.

FIG. 6 shows the handover in the other direction (from DBS to RBS). Thehandover process is similar to the regular inter-BS handover process,with the exception of there being additional operations between the RFUand DFU, as shown in the figure. Note that the RFU and DFU may snoop themessage traffic to identify relevant parameters, examples of which aredescribed in FIG. 5 and FIG. 6 illustrating handover in each direction.

Attention is now drawn to FIG. 7, which shows a network entry procedurefor a Recipient Function Unit according to an embodiment of the presentinvention. The procedure describes entry (also called “installation”)and authorization of an RFU in the network. The present embodimentassumes that an operator may install the RFU under any DFU in itsnetwork.

The Donor BS shown in the present embodiment may be any Serving BS (e.g.a WiMAX BS), with the additional capabilities provided by a DFU asdescribed in this disclosure.

The process illustrated in FIG. 7 may include some of the featuresenumerated in the following list. Again, it should be noted that theseare described in terms of a WiMAX implementation by way of example onlyand should not be construed as limiting.

-   -   The RFU may use a dummy or a real authentication method with        EAP/PKMv2. The authentication is not exposed to the rest of the        WiMAX network (ASN GW, AAA (Authentication, Authorization &        Accounting Server, which is used for the authorization and        authentication of the subscriber into the network and service)),        as shown in FIG. 7.    -   The RFU uses an authenticated mode for entering the network,        however the DFU intercepts the authentication process so that        the RFU Network Entry is not exposed to the ASN Gateway). In a        possible implementation of the authentication process both sides        (DFU and RFU) are preconfigured with a MSK (Master Session Key)        to be used for deriving other security context (as per 802.16e).    -   The DFU may identify the RFU using an indication during INE        (Initial Network Entry). As an example, the DFU may be        pre-provisioned with an RFU's MS ID (MAC address) to distinguish        the RFU from other devices (e.g., MS).    -   Both sides may support traffic encryption and CMAC for security        purposes.    -   Both sides may establish two types of bi-directional datapaths        (CIDs): one type for control traffic (R6/R8 control) and a        second one for user traffic (e.g., GRE encapsulation).    -   As noted above, header compression may be supported.    -   RBS management traffic may also be delivered—classified to        dedicated CIDs between the RFU and the DFU.

Another feature of embodiments of the present invention concerns the RBS(IP host) address allocation. With respect to this feature, in someembodiments, the following rules may apply:

-   -   RBS IP address allocation is the same as for any other BS in the        network.    -   RBS IP address is from the same IP space as other ASN elements        (e.g., BSs, ASN GW).

In the case of ASN bridging transport (L2), DBS and all RFUs attached tothis Donor BS are assigned to the same IP subnet.

Attention is now drawn to FIG. 8, which shows an initial network entryprocedure of a mobile subscriber to a Remote Base Station, includingspecial handling between an RFU and DBS according to an embodiment ofthe present invention. Note that the RFU and DFU may snoop the messagetraffic to identify relevant parameters, examples of which are describedin the figure.

Some factors to note with regard to network entry, handoff SF (serviceflow) management, and deregistration procedures may include thefollowing

-   -   DFU and/or RFU may snoop or relay R6 datapath messages (e.g.,        Establishment/Deregistration/Modify) in order to derive Session        ID (GRE Key) and QoS parameters of the flow running through an        in-band backhauling segment. When snooping discovers parameters        that are intended to affect the R6 datapath control, such        parameters may be mapped to their corresponding R1 datapath        control parameters, thereby supplying the desired relative flow        as specified in the encapsulated R6 datapath control messages.    -   Session ID (GRE Key) information may be used for two purposes by        DFIJ and/or RFU:        -   To utilize the in-band backhauling segment by compressing            the GRE header on the air (i.e., in-band backhauling            segment).        -   To keep the session context per Session ID for bandwidth            management    -   Other R6/R8 control messages might not be intercepted by the DFU        and/or RFU.

In some embodiments of the in-band-backhauling segment, the followingbandwidth and QoS management mechanisms may be applied. These examplesare taken from WiMAX implementations, but should not be considered aslimiting to that domain. The following mechanisms may be used to improvethe utilization of the in-band-backhauling traffic (i.e., improve theuse of the in-band BH segment's capacity) and reducing controllatencies.

-   -   To optimize user traffic utilization it is possible (though not        required) to use shared CIDs (Connection IDs) for users/SFs        (MSs/GRE Keys). It is also possible to use a dedicated CID per        SF. In some embodiments, for example, an RBS may serve many MSs,        where each MS may have multiple Service Flows (SFs). By using        shared CIDs, the system does not expose to the in-band virtual        BH segment all the SFs, but maps them to a limited number of        connections (CIDs) of the R1 interface. This use of shared CIDs        provides greatly improved utilization of the in-band BH segment        as it dramatically reduces the number of the managed CIDs (e.g.,        can replace tens of CIDs by three to five pairs).    -   For bandwidth management each R6 datapath event (as described        above) may include bandwidth reservation information.    -   In order to reduce control relay time, a DBS can enable higher        priority to control messages (e.g., provide a dedicated CID for        R6/R8 control).    -   DBS and RFU may also apply QoS policies based on the TOS (Type        of Service) marking of the MS-traffic outer header.

With regard to network planning, an embodiment of an in-band backhaulingsystem may use various models to enable traffic forwarding between theelements within an ASN (Access Service Network) in a WiMAX system, forexample.

-   -   When a DBS and RFU are connected via WiMAX, only an L3        connection exists between them. In such a case, the DBS and RFU        must each provide functionality similar to that provided by        Proxy ARP (Address Resolution Protocol). Ordinary Proxy ARP        cannot be used in this case, due to the lack of a continuous L2        connection between elements of the core network and the RBSs        served by the RFU (i.e., as noted there is only an L3        connection). To address this problem, the RFU can proxy for        elements in the core network vis-à-vis the RBSs and the DBS can        proxy for the connected RBSs vis-à-vis the core network        elements.    -   For example, if an RBS needs to send a packet to the ASN        gateway, it would send an ARP request asking for the MAC address        corresponding to the ASN GW's IP address. Ordinarily, the ASN GW        would respond, but in the example cited here, it cannot due to        the lack of a continuous L2 connection. Therefore, the RFU        intercepts and replies with its own MAC address and, using the        virtual link, the RFU handles delivering the packet to the ASN        GW. A similar procedure would apply for the other direction with        the DBS proxying for the RBS vis-à-vis the ASN GW.    -   Another possible embodiment is the use of ASN Relay        functionality (as specified by the WiMAX NWG (Network Working        Group)). In such embodiments, the RFU and DFU are used as ASN        Relays for the RBS and ASN gateway respectively.

An in-band-backhauled base station is an RBS backhauled through an RFUand a DBS as described in this disclosure. Such a base station mayprovide at least some of the following advantages:

-   -   1. Economic: the costs for base station backhauling        infrastructure using the means available according to the prior        art, such as a hardwired connection, are avoided.    -   2. Simplicity of deployment: Extending a wireless network with        additional base stations may be accomplished without the cost        and time considerations of construction, wiring, and        administrative overhead (e.g., for obtaining legal right-of-way        for communication lines), etc.    -   3. Network management: Each RBS is an ordinary base station that        may be managed like any other base station, applying policies        appropriate for that base station. For example, Company A may        come to an agreement to in-band-backhaul an RBS through a DBS at        company B. Each company can manage its respective base station        according to each company's policies—such management would be        impossible with a repeater.    -   4. Flexibility: A DBS can self-manage its load by delegating        (i.e., handing off its SSs to its RBSs for overlapping areas of        coverage. This can also improve performance by eliminating the        bottleneck that could otherwise occur at a base station        augmented by repeaters.    -   5. Performance: By using additional BSs with the RFU, processing        that is latency sensitive (e.g., scheduling, ARQ handling) can        be handled locally by the RBS, thus reducing latency and        improving the user experience for SSs.    -   6. Coverage: Often there are isolated areas within the coverage        area of a wireless base station where communication is not        reliable. The lack of reliability may be due, for example, to        topographic features or other obstructions, such as buildings.        The deployment of an in-band-backhauled base station can address        this coverage problem and increase the capacity of the wireless        network.

It is expected that during the life of this patent many relevant devicesand systems will be developed and the scope of the terms herein,particularly of the terms backhauling, gateway, base station, subscriberstation, mobile subscriber, serving base station, target base station,all WiMAX-specific terminology and examples, all Internet Protocolterminology and examples, and all OSI Reference Model terminology andexamples, is intended to include all such new technologies a priori.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents, and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

What is claimed is:
 1. A method for providing in-band backhauling from afirst base station to a second base station in a wireless communicationnetwork, said method comprising: connecting a device to a first basestation, said device comprising: a) a backhauling interface unit forphysically connecting to and interfacing with said first base stationusing a standard backhaul interface and a standard backhaul protocol toand from the first base station, said backhauling interface unitcomprising logic for providing a standard backhauling interface forbackhauling from the first base station, and b) an air interface unitfor connecting to said first backhauling interface unit, comprisinglogic for encapsulating, within a subscriber station communicationsprotocol, backhaul communications in the standard backhaul protocolreceived from said backhauling interface unit, for wirelesslytransmitting the encapsulated backhaul communications to a second basestation, the second base station being configured to provide backhaulingfrom and to the first base station and from and to a core network, andde-encapsulating backhaul communications received from the second basestation in the subscriber station communications protocol, wherein thebackhauling interface unit, the air interface unit and the second basestation jointly provide a channel for backhauling from the first basestation.
 2. The method of claim 1 and further comprising using thedevice for: receiving encapsulated backhaul communications from thesecond base station; and de-encapsulating the encapsulated backhaulcommunications received from the second base station.
 3. The method ofclaim 1 in which the encapsulating backhaul communications comprisesencapsulation at standard network layer
 2. 4. The method of claim 1 inwhich the encapsulating backhaul communications comprises encapsulationat standard network layer 3.